1. Field of the Invention
Exemplary embodiments of the present invention relate to a cylindrical underwater vehicle with a propulsion control blade mounted to the rear thereof for controlling propulsion of the underwater vehicle; and, particularly, to a cylindrical underwater vehicle with a vertical end plate attached to a partially movable rudder, including a vertical end plate which is formed to have a regular width in a longitudinal direction of the underwater vehicle and is mounted on a circumference thereof in order to improve a control force for the underwater vehicle.
2. Description of Related Art
A cylindrical underwater vehicle, such as a torpedo moving under water, includes, at the rear thereof, a propeller to generate a propulsive force, a duct to protect the propeller, propulsion control blades to control a propulsion direction of the cylindrical underwater vehicle under water, etc.
For example, a propulsion control blade as shown in FIG. 1 is mounted to the rear of an underwater vehicle. The propulsion control blade includes a fixed plate 121 which is formed at intervals in a radial direction of the underwater vehicle, and a movable plate 122 which is rotatably mounted to a portion of the rear of the fixed plate 121. The fixed plate 121 is formed in plural numbers along a circumference of the underwater vehicle, and the movable plate 122 is rotatably mounted, at a front end thereof, to the rear of each fixed plate 121 (hereinafter, the propulsion control blade being referred to as “a partially movable rudder” since only the movable plate rotates).
Such a partially movable rudder allows overall movement of the underwater vehicle to be controlled by the fixed plate 121 and additionally rotates the movable plate 122 by a desired angle, so that the propulsion of the underwater vehicle may be accurately controlled.
However, the partially movable rudder of the cylindrical underwater vehicle according to the prior art cannot help having a limited shape.
Since the cylindrical underwater vehicle such as a torpedo has a maximum diameter equal to or less than an inner diameter of a launch tube, the partially movable rudder, namely, the fixed plate 121 and the movable plate 122 cannot help being limited in size and shape.
According to the propulsion control blade of the prior art, due to the above-mentioned limit of the shape, a vortex is generated at an edge portion of the propulsion control blade while fluid moves from a high-pressure portion to a low-pressure portion by a pressure difference between opposite surfaces of the propulsion control blade.
For example, FIG. 2 shows distribution of a vorticity field by the movable plate 122 in the propulsion control blade of the cylindrical underwater vehicle as described above. As shown in FIG. 2, the vorticity field is distributed at a position of n times in a longitudinal direction of the movable plate. Here, it may be seen that a large vorticity field by the movable plate 122 is generated at a portion indicated by a red color and deep color.
Since such a vortex causes a reduction in lift and an increase in resistance, the propulsive force of the underwater vehicle may be decreased and further the underwater vehicle may not be accurately controlled.